Varactor diode frequency multipliers are well known in the art. Typical varactor diode frequency multipliers are either triplers or doublers. It is known to connect such frequency multipliers in cascaded chains so as to provide a selected multiplication factor. Usually an isolator is provided between the individual frequency multipliers so as to prevent interference therebetween.
A typical frequency multiplier chain is described in an article entitled "10 to 40 GHz Doubler-Doubler Chain for Satcom Applications", by P. W. Staecker and R. W. Chick, published in Microwave Journal, December 1985, pp. 87-108.
MMW (millimeter wave) varactor diode frequency multipliers are employed in various MMW communications systems, such as transceivers, RF heads, and the like. In many applications there is used a cascaded frequency multiplier chain, similar to that described in the above-referenced article.
As is well known to persons skilled in the art, as varactor diode frequency multipliers are manufactured for use as individual frequency multipliers of a cascaded chain, each such multiplier is manufactured with both input and output matching networks. For frequency multipliers manufactured for use in MMW and high microwave range applications matching networks are typically in the form of stepped waveguides.
In a cascaded frequency multiplier chain of two or more frequency multipliers, the output frequency of the first multiplier is the same as the input frequency of the second multiplier. Accordingly, the output matching network of the first multiplier and the input matching network of the second multiplier are provided in the form of similar stepped waveguides.
Accordingly, among disadvantages of cascaded chain arrangements of conventional varactor diode frequency multipliers is that they are very expensive to manufacture, due mainly to the provision of a large number of highly accurate machined parts, including stepped waveguides. Furthermore, the efficiency of such cascaded chains is reduced due to the provision of isolators between their constituent frequency multipliers and due to the matching networks therebetween. It would also be desirable to reduce the weight and size of varactor diode frequency multiplier chains to a minimum.
Frequency multiplier chains are described in the following articles:
"Development of a 750 GHz Solid State Source", published in Conference Proceedings, 21st European Microwave Conference, Microwave '91 pp. 237-42 by B. N. Lyons, T. E. O'Ciardha, U. S. Lidholm, and B. L. A. Rydberg;
"Single-Balanced Mixer Forms Dual MM-Wave Frequency Multiplier", published in Microwaves and RF, vol. 29, no. 10, pp. 81-82 and 84-86 by B. C. Henderson and A. W. Denning;
"Frequency Multiplication by a Prime Number Using Multiplier Chains" published in 1978 IEEE MTT-S International Microwave Symposium Digest, pp. 321-322 by A. I. Grayzel and W. Emswiler;
"Stacked Varactors with Four Snap-Off Diodes in Series for Very High Power Multipliers", published in 1973 European Microwave Conference, Vol. I, pp. A4-5/4 by R. M. Henry;
"Active Solid-State Devices", published in Bell System Technical Journal, Vol. 47, no. 7, pp. 1323-1377 by H. E. Elder;
"Capability of Schottky-Diode Multipliers as Local Oscillators at 1 THz", published in Microwave and Optical Technology Letters, Vol. 4, no. 1, pp. 29-33 by A. Raisanen and M. Sironen;
"High Power Epitaxially Stacked Varactor Diode Multipliers: Performance and Applications at W-band", published in 1990 IEEE MTT-S International Symposium Digest (Cat. No. 90CH2828-0), pp. 923-926, Vol. 2 by J. F. Cushman, F. Occhiuti, E. M. McDonagh, M. E. Hines and P. W. Staecker;
"High-output, Single- and Dual-diode, Millimeter-wave Frequency Doublers", published in IEEE Transactions on Microwave Theory and Techniques, Vol. MTT-33, no. 6, pp. 533-538 by J. W. Archer and M. T. Faber; and
"Integrated Stripline Multiplier Chain", published in the Proceedings of the 1971 European Microwave Conference Part II, p. C10/5 by L. Afzelius, B. Hagaeus and G. Hanson.